48 lines
2.4 KiB
Markdown
48 lines
2.4 KiB
Markdown
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# 260614 — Project Xanadu deep dive (the docuverse, the EDL, reference-not-copy)
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Date: 2026-06-14
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## What this is
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A focused study of **Project Xanadu** (Ted Nelson) read through shard-wiki's lens.
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Unlike the engine dives (`xwiki`, `twiki`, `foswiki`), Xanadu is **not a candidate
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shard backend** — it never shipped at scale and there is nothing to attach. It is
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studied as the **deepest conceptual ancestor** of shard-wiki's own model: several
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shard-wiki primitives turn out to be Xanadu mechanisms under different names.
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The distinctive material:
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- the **EDL / xanadoc** — a document that contains *no content*, only an ordered list
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of **spans** (content references) plus **xanalinks** (separate link tables); the
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client assembles the page by reference → this is shard-wiki **projection** + **union**
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- the storage substrate — **tumblers** (stable fine-grained addresses), **istream**
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(invariant content pool), **enfilades / spanfilade** (virtual↔content mapping,
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version comparison by span-set intersection)
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- **content-identity, bidirectional transclusion** — content "knowably in more than
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one place" that remembers all its appearances → stronger than UC-32
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- **transcopyright / micropayment** — a baked-in rights policy shard-wiki must keep
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*configurable*, not inherit
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Goes deliberately **underneath** the surface pattern table in
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`research/260608-federation-concepts/findings.md` §3.3, which it extends rather than
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repeats.
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## Contents
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| Path | Role |
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|------|------|
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| `findings.md` | EDL/xanadoc, addressing substrate, transclusion, versioning, rights, INTENT mapping (reinforcements + design-bug divergences), UC seeds, architecture notes, sources |
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## Status
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Initial deep dive complete. Three new use cases promoted to `spec/UseCaseCatalog.md`
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(UC-44 compose-by-reference, UC-45 reverse transclusion, UC-46 content-identity
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equivalence); UC-24/27/29/32 enriched. Span-addressing as an adapter capability,
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content identity, composition manifests, and reuse-terms metadata logged as
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architecture for `workplans/SHARD-WP-0002-federation-architecture.md`.
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Key boundary recorded: shard-wiki inherits Xanadu's **reference-not-copy** mechanisms
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but **rejects** the single-global-docuverse premise, the single-canonical-instance
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model, and the baked-in economic policy — those would violate shard sovereignty,
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parallel-version support (UC-27), and mechanism-over-policy.
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</content>
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